The invention relates to a guide element and a device for penetrating extension of a blind hole introduced into hard tissue, in particular into the jaw bone.
Such an extension of a bone bore is for example required in the filed of dental surgery when performing a procedure referred to as sinus lift. Sinus lift means an operation in which the mucosa of the maxillary sinus or sinus membrane or Schneider's membrane is partially detached and lifted to create a space between the bone and the mucosa of the maxillary sinus. Into the created hollow space, an autologous bone, for example from the tuber maxillae, the linea obliqua, the chin region or from the hip crest (bone replacement materials, bone graft) or a synthetic bone replacement material, for example bone replacement material of the brand Bio-Oss® from the company Geistlich AG, often mixed with autologous bone, is then introduced. This material is intended to convert into bone within 6 months, to ensure a solid base for an implant.
The conventional approach for a sinus lift is to prepare a mucoperiostal flap, buccally in the region of the molars, and to mill an oval window into the thus exposed bone, without damaging the underlying mucosa of the maxillary sinus. The oval bone disc which his attached to the mucosa of the maxillary sinus is then carefully pushed in the direction of the maxillary sinus, wherein the mucosa of the maxillary sinus is carefully detached from the bone around the window using special instruments. Because the mucosa of the maxillary sinus is very fragile, comparable to the chorion of an egg, this procedure has to be performed very carefully because of the risk of damaging the mucosa of the maxillary sinus. The space which is thus created in the maxillary sinus is then filled with the bone replacement material and the buccal window is covered with a film. Generally, the film is made of an absorbable material such as a membrane of the brand Bio-Gide® of the company Geistlich AG. After this, the mucoperiostal flap is densely sutured up. This method is relatively invasive and causes stress to the patient due to strong swelling and discoloration up to 10 days, and may also involve pain. This surgical procedure is often also referred to as “open” or “classical” sinus lift. In case a sufficient residual bone height remains, e.g. a height of 5 mm, the implants can be inserted at the same time of the sinus lift (one time sinus lift). The implants can be exposed to full load only after solidification of the bone replacement material. When the residual bone height is too thin, the insertion of the implants is performed in a second procedure about 6-8 months after the sinus lift (second sinus lift).
A newer method is the so called crestal sinus lift which does not require folding open of the bone plate. Access to the maxillary sinus is enabled from the jaw crest. At the toothless portion of the jaw crest, the oral mucosa is punched through up to the bone by means of a specially provided punch (Jesch's punch) and a blind hole is milled into the bone up to just below the mucosa of the maxillary sinus with a cylindrical milling machine. The punch used for this, automatically lifts the mucosal disc from the bone and creates a central through hole for the further bore or milling. The bore is milled below the bony sinus floor generally antral i.e., starting from the crest by means of a cylindrical milling tool for example with a diameter of 3.5 to about 1 mm, wherein the bone thickness is previously measured by means of X-ray. Because the mucosa of the maxillary sinus must not be damaged by the milling tool, the jaw bone must not be fully drilled through with the milling tool, so that at the bottom of the blind hole a thin bone plate remains, against the backside of which the mucosa of the maxillary sinus rests. Conventionally, this thin bone plate is then carefully pushed in the direction of the maxillary sinus with a cylindrical instrument, so that it is pushed in the direction of the maxillary sinus along with the mucosa of the maxillary sinus which is attached above the bone disc to the top of the bone disc. This “puncturing” of the bone disc is a critical point for the procedure because an excessive pushing-in of the bone disc leads to the mucosa of the maxillary sinus being lifted tent-shape and being tensioned, which may lead to damage to the mucosa of the maxillary sinus. The mucosa of the maxillary sinus is then carefully lifted, and the bone replacement material is then introduced into the newly created free space via the bore. The implant is then anchored mostly directly in the bore.
Even though very advanced methods have been developed to detach the mucosa of the maxillary sinus as carefully as possible and sufficiently far away from the jaw bone through the small bore, which mostly has a diameter of only about 4 mm, the moment at which the jaw bone is perforated remains a critical moment which requires great experience and particular skill of the doctor, wherein even when taking all precautions, there is still a residual risk of causing damage to the mucosa of the maxillary sinus when perforating the bone plate. In order to make the sinus lift-procedure safer, means are desired which facilitate this penetrating extension of the jaw bone bore, and at the same time lower the risk of damage to the fragile sinus membrane behind the jaw bone.
Such an advantageous means is known from WO 2010/048648 A1, where a device is described which has a tubular body with a distal working opening and an entry opposite the working opening, which entry is closed by a sealing element which is traversed by a shaft of a working tool, e.g. of a milling tool. On the tubular body, a connection for applying an internal pressure is arranged. The tubular body is sealingly inserted into a blind hole which was previously introduced into the jaw bone, wherein the distal working opening rests against the end of the blind hole thereby mostly sealing the inner space. The working medium inside the tubular body, preferably NaCl solution, can now be pressurized via the connection, for example by means of a syringe connected to the connection. With the working tool, which can be controlled from outside, the bone disc which remains between the blind hole and the maxillary sinus is milled off in the region of the working opening. At the moment when the head of the working tool penetrates the bone and enters into the region below the sinus membrane, the overpressure in the interior of the tubular body, causes the working medium to enter through the free opening and to push the sinus membrane located there behind away from the bone and with this out of the working area of the working tool and out the zone of danger. The discharge of the working medium causes the pressure to decrease which indicates the perforation of the bone and also prevents an excessive bloating of the sinus membrane.
Such a device is safe to operate, and excellent surgical result with minimal risk to the mucosa of the maxillary sinus can be achieved with such a device. However, a certain disadvantage is that cleaning of the device is relatively costly and difficult. In particular, it is very difficult to clean the thin connection channel via which the pressure medium is supplied into the tubular body or the pressure chamber, thoroughly enough so that no contaminations remain. Generally, each reuse of medical equipment or products in the field of surgery bears certain infection risks for the patient and any contamination can lead to health problems, disease or even death of the patient. Although thorough re-sterilization of the device allows killing a predominant portion of the germs, such a re-sterilization is time consuming, exposes the material to stress and is cost intensive and still does not exclude a certain residual risk of a microbial contamination.